Recently, various diseases such as brain diseases, AIDS and genetic diseases have been intensely studied and many of their causative and related genes have been revealed. Accompanied therewith, great hopes have been placed on gene delivery aiming at elucidation of the function of a target gene in basic research fields, and gene therapy for diseases in advanced medical fields.
Calcium phosphate reagents, DEAE-dextran reagents, liposome reagents (e.g., Lipofectamine 2000, Lipofectin, etc.) and the like are known as reagents commercially available for gene delivery into cultured cells. In many cases, however, they are cytotoxic, show low introduction efficiency into normal cells and have a problem that introduction efficiency reduces in the presence of serum. Moreover, these reagents are not applicable to the gene delivery into experimental animals and human. While methods using a device such as microinjection method, electroporation method, particle bombardment (gene gun) method and the like, show relatively high introduction efficiency, there are problems that they require expensive devices and a lot of skill, throughput is low and the like. Since techniques for gene delivery using viral vectors have superior introduction efficiency into and gene expression capability in normal cells, they are attracting the highest attention in gene therapy. However, due to the pathogenicity (e.g., tumor induction) and immunogenicity of virus in vivo (inactivation by neutralizing antibody), a more safe gene delivery technique is desired.
The present inventors have studied and developed cationic lipids capable of introducing a plasmid DNA or an siRNA into cultured or primary cells with a high efficiency, and reported those that are suitable for introducing a plasmid (WO 2005/054486) and those that are suitable for introducing an siRNA (Japanese Patent Application No. 2004-356071) from their own repertoire of cationic lipids (JP-B-1984767). Furthermore, the present inventors have found that a gene can be introduced into cultured cells with a high efficiency using glycolipids (Japanese Patent Application No. 2005-080759).